Stjxfonation oe hydrocarbons with soa



lit

water is formed as a by-product.

' UNITED srn'rns PATENT onnrcn.

CHARLES R. DOWNS, OF CLIFFSIDE, NEW JERSEY, ASSIGNOR 1'0 THE BARRETTCOMPANY, A. CORPORATION OF NEW JERSEY.

SULFONATION OF HYDROGARBONS WITH S03 no Drawing.

To all whom it may concern:

"Be it known that I, CHARLns R. Downs, a citizen of the United States,residing at Olifiside, in the county of Bergen and State of New Jersey,have invented certain new and useful Improvements in.Sulfonation ofHydrocarbons with S0,, of which the following is a specification.

This invention relates to a method of sulfonating hydrocarbons by meansof sulfur trioxid. It relates more particularly to the sulfonation ofaromatic hydrocarbons by the use of gaseous S0,. The invention hasparticular application in the sulfonation of benzene and naphthalene inthe vapor phase to reduce the monoor higher sulfonic aci s by means ofgaseous SO, such as the ordinary gas mixture obtained from the usualcontact chamber for producing S It is well known that when aromatichydrocarbons are treated with sulfuric acid, Due to the formation ofwater during ,the sulfonation it is necessary either to use moresulfuric acid than would otherwise be required,

because of the consequent dilution of the sulfuric acid, or the watermust be removed during the sulfonation process in order for thesulfonation to be completed.

When aromatic hydrocarbons aretreated in the liquid phase with SO tosulfonate the same, it is desirable to use pure SO in order to avoidcontamination of the prodnets with objectionable matter which is noteasily removed. Since the ordinary SO from the contact chambers isusually mixed with some S0,, and nitrogen and other impurities, thesulfonation products will be conglaminated when such impure S0 is use Bymy invention it is possible to use SO from the contact chambers for thesulfonation of aromatic hydrocarbons, thereby obviating the formation ofwater as a by-prodnot, and also preventing the mixture of otheriropurities with the sulfonic acids to any appreciable extent. Incarrying out this invention thearomatic hydrocarbon in the vapor phase,admixed with SO from the contact chambers, is passed through vessels ortubes heated to the proper temperature for the sulfonation to takeplace. The rapidity and degree of sulfonation and the formation of themono-sulfonic acid or higher sulfonic acids and the position thatSpecification of Letters Eatent.

Patented Nov. 18, 1919.

Application filed .Tune 11, 1919. Serial No. 303,338.

the 'sulfonic acid group will take will depend upon many factors such asthe temperature at which the reaction is caused to take place, thelength of time the S0 is kept in contact with the hydrocarbon, thedilution of the S0 with blanketing gases, such as nitrogen, theparticular hydrocarbon used, and the pressure that is maintained inthesystem. These factors can be easily ascertained by trial so as toproduce the desired results. When the proper proportion of hydrocarbonand S0 is passed through the hot space substantially all of the S0 willreact without the formation of any water, or the waste of a substantialamount of 80,. For example, if the theoretically correct amount of S0 ispassed with naphthalene in the vapor phase through a tube heated betweenabout 90 C. and 180 (1, the mono-sulfonic acids of naphthalene will bemainly formed. 1

Upon exit of the reaction products from the hot-reaction chamber, thesulfonic acid will be easily condensed due to the fact that sulfonicacids have low 'vapor pressures, while the other gases, if present, willpass off. In this way. a substantially pure sul- I fonic acid will becondensed which is free from the presence of sulfuric acid or othersubstituting a hydroxyl for the sulfo radical of the sulfonic acid. Thispresent invention avoids this difficulty since the substantially puresulfonic acid resulting from the condensation of sulfonic acid vapor canbe neutralized directly by caustic or weak acid salts of the alkalinemetals without the necessity of precipitating GaSO For thisneutralization it is possible to use a caustic soda solution of suchstrengththat the sodium salt of the sulfonic acid is obtained as a watersolution of proper concentration to be used for the purpose abovementioned.

While this process has been articularly described in connection with t esulfonation of naphthalene, it is applicable to other hydrocarbons,particularly benzene and its homologues.

I clalm: V

1. The herein described process which comprises treating an aromatichydrocarbon in the vapor phase with a gas containing SO under suchconditions as to efiect sulfonation of the aromatic hydrocarbon.

2. The herein described process which comprises treating an aromat1chydrocarbon in the vapor phase with a gas containing S0 under suchconditions as to efiect sulfonation of the aromatic hydrocarbon, andcondensing the sulfonic acids thereby formed.

' 3. The herein described process whichcomprises treating an aromatichydrocarbon in the vapor phase with a gas containing S0 under suchconditions as to effect sulfonation of the aromatic hydrocarbon,condensing the sulfonic acids thereby formed, and permitting theuncondensed gas to escape.

4. The herein described process which comprises treating an aromatlchydrocarbon in the vapor phase with gaseous SO under such conditions asto efiect sulfonationof the aromatic hydrocarbon.

5. The herein described process which comprises treating an aromatlchydrocarbon in -the vapor phase with aseous SO under such conditions asto e ect sulfonation of the aromatic hydrocarbon, and condensing thesulfonic acids thereby formed.

6. The herein described process which comprises treating an aromatichydrocarbon in t e vapor phase with a gas containing S0 under suchconditions as to efi'ect sulfonation of the aromatic hydrocarbon,condensing the sulfonic acids thereby formed,

I and directly neutralizing .said acids.

7. The herein described process which comprises treating an aromatichydrocarbon in the vapor phase with a gas containing SO under suchconditions as to effect sulfonation of the aromatic hydrocarbon,condensing the sulfonic acids thereby formed, and directly neutralizingsaid acids with a compound containing an alkali.

8. The herein described process which comprises treating an aromatichydrocarbon in the vapor phase with a gas containing SO under suchconditions as to effect sulfonation of the aromatic hydrocarbon,condensing the sulfonic acids thereby formed, and directly neutralizingsaid acids with caustic soda solution of such concentration that a watersolution of sodium sulfonate will'be formed.

9. The herein described process which comprises treating naphthalene inthe vapor phase'with a gas containin SO under such conditions as toeifect su fonation of the naphthalene.

10. The herein described process which comprises treating naphthalene inthe vapor phase with a gas containing SO under such conditions as toeffect sulfonation of the naphthalene, condensing and neutralizing thesulfonic acid thereby formed.

11. The herein described process which comprises passing naphthalene andS0 through a confined space at a temperature between 90 CL and 180 C.

12. The herein described process which comprises treating naphthalene inthe vapor phase with a gas containing SO under such conditions as toeffect sulfonation of the naphthalene, and condensing the sulfonlc acidthereby formed at a temperature below that at which the major portion ofthe other gases will be condensed.

In testimony whereof I aflix my signature.

CHARLES R. DOWNS.

